Fungal infection is a major healthcare problem, and the incidence of hospital-acquired fungal diseases continues to rise. Severe systemic fungal infection in hospitals (such as candidiasis, aspergillosis, histoplasmosis, blastomycosis and coccidioidomycosis) is commonly seen in neutropaenic patients following chemotherapy and in other oncology patients with immune suppression, in patients who are immune-compromised due to Acquired Immune Deficiency Syndrome (AIDS) caused by HIV infection, and in patients in intensive care. Systemic fungal infections cause ˜25% of infection-related deaths in leukaemics. Infections due to Candida species are the fourth most important cause of nosocomial bloodstream infection. Serious fungal infections may cause 5-10% of deaths in patients undergoing lung, pancreas or liver transplantation. Treatment failures are still very common with all systemic mycoses. Secondary resistance also arises. Thus, there remains an increasing need for effective new therapy against mycotic infections.
Enfumafungin is a hemiacetal triterpene glycoside that is produced in fermentations of a Hormonema spp. associated with living leaves of Juniperus communis (U.S. Pat. No. 5,756,472; Pelaez et al., Systematic and Applied Microbiology, 23:333-343, 2000; Schwartz et al., JACS, 122:4882-4886, 2000; Schwartz, R. E., Expert Opinion on Therapeutic Patents, 11(11):1761-1772, 2001). Enfumafungin is one of the several triterpene glycosides that have in vitro antifungal activities. The mode of the antifungal action of enfumafungin and other antifungal triterpenoid glycosides was determined to be the inhibition of fungal cell wall glucan synthesis by their specific action on (1,3)-β-D-glucan synthase (Onishi et al., Antimicrobial Agents and Chemotherapy, 44:368-377, 2000; Pelaez et al., Systematic and Applied Microbiology, 23:333-343, 2000). 1,3-β-D-Glucan synthase remains an attractive target for antifungal drug action because it is present in many pathogenic fungi which affords broad antifungal spectrum and there is no mammalian counterpart and as such, compounds specifically inhibiting 1,3-β-D-Glucan synthase have little or no mechanism-based toxicity.
Various enfumafungin derivatives have been disclosed, e.g., in International Patent Publication Nos. WO 2007/126900 and WO 2007/127012.